The invention discloses application of the combination of zoledronic acid and an organic selenium compound in preparation of antitumor drugs. In-vitro cell experiments show that the inhibiting effectof the organic selenium compound alone or the zoledronic acid alone on tumor cells is not as good as that of the combination of the two, and the combination of the two can achieve a synergistic effect, that is, the synergistic effect of the organic selenium compound and the zoledronic acid can be utilized to efficiently induce apoptosis of the tumor cells. According to the application, the potential mechanism of action, in which the ability of the organic selenium compound to inhibit the growth of prostate cancer cells is enhanced by the zoledronic acid, is caused by the fact that the cells are induced to generate excessive ROS (reactive oxygen species). The zoledronic acid and the organic selenium compound can be combined to prepare the antitumor drugs, or the zoledronic acid is used as asensitizer for the organic selenium compound and is applied to the field of tumor therapy.